In the packaging of integrated circuits, a device die may be bonded to another package component such as a Printed Circuit Board (PCB), a package substrate, an interposer, another device die, or the like. The bonding methods include direct metal-to-metal bonding, solder bonding, fusion bonding, hybrid bonding, and the like.
To meet the requirement of the increased integration level, more applications may be integrated into a same package. This causes the number of electrical connectors (such as solder balls) that are used for bonding to increase dramatically. The increase in the number of solder balls, however, results in other problems. For example, the device dies, the package substrates, and the PCBs could have warpage and CTE mismatch. The warpage and CTE mismatch could cause the variation in the standoff distance between the bonded package components, which results in reliability problems.